arnaucube/chip8-rs
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u8 operations with wrapping to avoid overflow

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arnaucube
2020-10-19 20:44:08 +02:00
parent d68feb1fd9
commit 0d75e866a9
7 changed files with 40 additions and 29 deletions
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13
README.md
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@@ -1,6 +1,17 @@
# chip8-rs # chip8-rs
CHIP-8 emulator written in Rust. CHIP-8 emulator written in Rust.
(Done with the Go implementation: https://github.com/arnaucube/go-chip8)
*(Done with the Go implementation: https://github.com/arnaucube/go-chip8)*
https://en.wikipedia.org/wiki/CHIP-8 https://en.wikipedia.org/wiki/CHIP-8
## Usage
```
./chip8-rs --file roms/invaders.c8
```
![](screenshots/s0.png)
![](screenshots/s1.png)
![](screenshots/s2.png)
![](screenshots/s3.png)

35
chip8/src/lib.rs
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@@ -15,7 +15,7 @@ pub struct Chip8 {
delay_timer: u8, delay_timer: u8,
sound_timer: u8, sound_timer: u8,
stack: [u16; 16], stack: [u16; 16],
sp: isize, sp: usize,
pub key: [u8; 16], pub key: [u8; 16],
pub draw_flag: bool, pub draw_flag: bool,
} }
@@ -77,7 +77,7 @@ impl Chip8 {
let y: usize = ((self.opcode & 0x00F0) >> 4) as usize; let y: usize = ((self.opcode & 0x00F0) >> 4) as usize;
let nn: u8 = (self.opcode & 0x00FF) as u8; let nn: u8 = (self.opcode & 0x00FF) as u8;
let nnn: u16 = (self.opcode & 0x0FFF) as u16; let nnn: u16 = (self.opcode & 0x0FFF) as u16;
// println!("{:?} {:?}", self.opcode, self.pc); // println!("{:x} {:?}", self.opcode, self.pc);
// Decode Opcode // Decode Opcode
// https://en.wikipedia.org/wiki/CHIP-8#Opcode_table // https://en.wikipedia.org/wiki/CHIP-8#Opcode_table
@@ -95,10 +95,10 @@ impl Chip8 {
0x000E => { 0x000E => {
// 00EE Returns from a subroutine // 00EE Returns from a subroutine
self.sp -= 1; self.sp -= 1;
self.pc = self.stack[self.sp as usize]; self.pc = self.stack[self.sp];
self.pc += 2; self.pc += 2;
} }
_ => println!("unk {:x}", self.opcode), _ => println!("Unknown opcode: {:x}", self.opcode),
} }
} }
0x1000 => { 0x1000 => {
@@ -107,7 +107,7 @@ impl Chip8 {
} }
0x2000 => { 0x2000 => {
// 2NNN Calls subroutine at NNN // 2NNN Calls subroutine at NNN
self.stack[self.sp as usize] = self.pc; self.stack[self.sp] = self.pc;
self.sp += 1; self.sp += 1;
self.pc = nnn; self.pc = nnn;
} }
@@ -143,7 +143,7 @@ impl Chip8 {
} }
0x7000 => { 0x7000 => {
// 7XNN Adds NN to VX. (Carry flag is not changed) // 7XNN Adds NN to VX. (Carry flag is not changed)
self.v[x] += nn; self.v[x] = self.v[x].wrapping_add(nn);
self.pc += 2; self.pc += 2;
} }
0x8000 => { 0x8000 => {
@@ -176,7 +176,7 @@ impl Chip8 {
} else { } else {
self.v[0xF] = 0; self.v[0xF] = 0;
} }
self.v[x] += self.v[y]; self.v[x] = self.v[x].wrapping_add(self.v[y]);
self.pc += 2; self.pc += 2;
} }
0x0005 => { 0x0005 => {
@@ -187,7 +187,7 @@ impl Chip8 {
} else { } else {
self.v[0xF] = 0; self.v[0xF] = 0;
} }
self.v[x] -= self.v[y]; self.v[x] = self.v[x].wrapping_sub(self.v[y]);
self.pc += 2; self.pc += 2;
} }
0x0006 => { 0x0006 => {
@@ -198,7 +198,7 @@ impl Chip8 {
} else { } else {
self.v[0xF] = 0; self.v[0xF] = 0;
} }
self.v[x] = self.v[x] >> 1; self.v[x] = self.v[x].wrapping_shr(1);
self.pc += 2; self.pc += 2;
} }
0x0007 => { 0x0007 => {
@@ -209,7 +209,7 @@ impl Chip8 {
} else { } else {
self.v[0xF] = 0; self.v[0xF] = 0;
} }
self.v[x] = self.v[y] - self.v[x]; self.v[x] = self.v[y].wrapping_sub(self.v[x]);
self.pc += 2; self.pc += 2;
} }
0x000E => { 0x000E => {
@@ -220,10 +220,10 @@ impl Chip8 {
} else { } else {
self.v[0xF] = 0; self.v[0xF] = 0;
} }
self.v[x] = self.v[x] << 1; self.v[x] = self.v[x].wrapping_shl(1);
self.pc += 2; self.pc += 2;
} }
_ => println!("unk {:x}", self.opcode), _ => println!("Unknown opcode: {:x}", self.opcode),
} }
} }
0x9000 => { 0x9000 => {
@@ -243,7 +243,7 @@ impl Chip8 {
0xB000 => { 0xB000 => {
// BNNN Jumps to the address NNN plus V0 // BNNN Jumps to the address NNN plus V0
self.pc = nnn + self.v[0] as u16; self.pc = nnn + self.v[0] as u16;
self.pc += 2; // self.pc += 2;
} }
0xC000 => { 0xC000 => {
// CXNN Sets VX to the result of a bitwise and operation on a // CXNN Sets VX to the result of a bitwise and operation on a
@@ -275,9 +275,8 @@ impl Chip8 {
} }
if self.gfx[pos] == 1 { if self.gfx[pos] == 1 {
self.v[0xF] = 1; self.v[0xF] = 1;
} else {
self.gfx[pos] ^= 1;
} }
self.gfx[pos] ^= 1;
} }
} }
} }
@@ -305,7 +304,7 @@ impl Chip8 {
} }
self.pc += 2; self.pc += 2;
} }
_ => println!("unk {:x}", self.opcode), _ => println!("Unknown opcode: {:x}", self.opcode),
} }
} }
0xF000 => { 0xF000 => {
@@ -378,10 +377,10 @@ impl Chip8 {
} }
self.pc += 2; self.pc += 2;
} }
_ => println!("unk {:x}", self.opcode), _ => println!("Unknown opcode: {:x}", self.opcode),
} }
} }
_ => println!("opc {:x}", self.opcode), _ => println!("Unknown opcode: {:x}", self.opcode),
} }
if self.delay_timer > 0 { if self.delay_timer > 0 {
self.delay_timer -= 1; self.delay_timer -= 1;

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21
src/main.rs
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@@ -30,7 +30,7 @@ impl SdlEmulator {
let video_subsystem = sdl_context.video().unwrap(); let video_subsystem = sdl_context.video().unwrap();
let window = video_subsystem let window = video_subsystem
.window("rust-sdl2 demo", (w * zoom) as u32, (h * zoom) as u32) .window("chip8-rs", (w * zoom) as u32, (h * zoom) as u32)
.position_centered() .position_centered()
.build() .build()
.unwrap(); .unwrap();
@@ -45,14 +45,15 @@ impl SdlEmulator {
vkeys.insert(Keycode::Q, 0x04); vkeys.insert(Keycode::Q, 0x04);
vkeys.insert(Keycode::W, 0x05); vkeys.insert(Keycode::W, 0x05);
vkeys.insert(Keycode::E, 0x06); vkeys.insert(Keycode::E, 0x06);
vkeys.insert(Keycode::R, 0x07); vkeys.insert(Keycode::R, 0x0d);
vkeys.insert(Keycode::A, 0x08); vkeys.insert(Keycode::A, 0x07);
vkeys.insert(Keycode::S, 0x09); vkeys.insert(Keycode::S, 0x08);
vkeys.insert(Keycode::D, 0x0E); vkeys.insert(Keycode::D, 0x09);
vkeys.insert(Keycode::F, 0x0A); vkeys.insert(Keycode::F, 0x0e);
vkeys.insert(Keycode::Z, 0x00); vkeys.insert(Keycode::Z, 0x0a);
vkeys.insert(Keycode::X, 0x0B); vkeys.insert(Keycode::X, 0x00);
vkeys.insert(Keycode::V, 0x0F); vkeys.insert(Keycode::C, 0x0b);
vkeys.insert(Keycode::V, 0x0f);
SdlEmulator { SdlEmulator {
w, w,
@@ -152,6 +153,6 @@ fn main() {
e.draw_graphics(); e.draw_graphics();
} }
e.set_keys(); e.set_keys();
std::thread::sleep(time::Duration::from_millis(1000 / 60)); std::thread::sleep(time::Duration::from_millis(200 / 60));
} }
} }